No Sting in the Tail for Sterile Bisex Queensland Fruit Fly (Bactrocera tryoni Froggatt) Release Programs.

Olivia L Reynolds,Bernard C Dominiak,Terry Osborne,Damian Collins

doi:10.3390/insects13030269

Olivia L Reynolds, Bernard C Dominiak + Show 2 more

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https://doi.org/10.3390/insects13030269

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Abstract

Simple SummaryFruit fly (Tephritidae) present a global market-access issue for horticultural produce. A key method of control for tephritidae pests is the sterile insect technique (SIT). Australia has released a bisex strain, i.e., males and females of sterile Queensland fruit fly, Bactrocera tryoni Froggatt, although only the males contribute to wild-population decline. While the number of stings were higher in one SIT release orchard, compared with the control, we showed that sterile female B. tryoni released in large numbers do not lead to degraded or unmarketable fruit, and therefore are suitable for release in commercial nectarine, peach and plum orchards.Global markets do not tolerate the presence of fruit fly (Tephritidae) in horticultural produce. A key method of control for tephritidae pests, is the sterile insect technique (SIT). Several countries release a bisex strain, i.e., males and females, however the sterile male is the only sex which contributes to wild population declines when released en masse. In commercial orchards, there are concerns that sterile females released as part of bisex strains, may oviposit, i.e., ‘sting’ and cause damage to fruit, rendering it unmarketable. Australia has released a bisex strain of sterile Queensland fruit fly, Bactrocera tryoni Froggatt, for several decades to suppress wild pest populations, particularly in peri-urban and urban environments. Here, we assessed fruit damage in two commercially grown stone fruit orchards where bisex sterile B. tryoni were released, and in an orchard that did not receive sterile flies. The number of detected stings were higher in only one SIT release orchard, compared with the control; however, there was no difference between SIT and control orchards in the number of larvae detected. We showed that there is no evidence that sterile female B. tryoni released in large numbers caused stings, or damage that led to downgraded or unsaleable fruit. The bisex strain of sterile B. tryoni is recommended for use in commercial stone-fruit orchards, under the conditions in which this trial was conducted.

Highlights

Fresh fruit markets have nil tolerance for fruit fly (Tephritidae) damaged fruit.The sterile insect technique (SIT) is a form of biological control whereby large numbers of mass-produced insects are irradiated to render them sterile
Some SIT programs, such as for the Mediterranean fruit fly (Ceratitis capitita Wied.), have developed genetic sexing strains which facilitates the ready separation of the sexes so that only sterile males are released [4], the only sex which effectively contributes to SIT
While the use of bisex strains, i.e., male and female strains, as part of SIT programs was largely discontinued for C. capitata in the early 2000’s [5], other species may still be released as bisex strains, despite little published evidence of whether sterile females sting fruit, and whether these stings lead to the unmarketability of the fruit

Summary

Introduction

The sterile insect technique (SIT) is a form of biological control whereby large numbers of mass-produced insects are irradiated to render them sterile. These sterile insects are transported to release centres [1,2], and released into the target area to flood the wild pest population, reducing the possibility of mating occurring between wild females and wild males and the subsequent production of fertile eggs [3]. Some SIT programs, such as for the Mediterranean fruit fly (Ceratitis capitita Wied.), have developed genetic sexing strains which facilitates the ready separation of the sexes so that only sterile males are released [4], the only sex which effectively contributes to SIT.

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